Popular cholesterol drug tied to risk of kidney trouble

Charlie Fidelman, Postmedia News03.20.2013

This file photo shows 40 milligram tablets of Lipitor. The use of high potency cholesterol lowering drugs called statins may increase a person's risk of developing kidney failure, a new study suggests. The research found that when compared to low potency statin regimens, high potency statin use was linked to slightly higher rates of acute kidney injury serious enough to require hospitalization.

Statins are so widely prescribed as to be called the Aspirin of the 21st century, but their benefits are not universal - new evidence suggests that the cholesterol-lowering medication can lead to kidney damage.

A study examining the health records of two million patients in Canada, the United States and Britain found that people taking a high-strength version of the drug face a small but increased risk of acute kidney injury compared with those taking a weaker version.

Patients who started high-strength statins were 34 per cent more likely to be hospitalized for acute kidney injury than those who started low-potency statins in the first 120 days of treatment, the study found.

Conducted by the Canadian Network for Observational Drug Effect Studies, the study published in the latest issue of British Medical Journal suggests doctors and patients should re-evaluate whether the risk of treatment at high doses is worth the benefits.

The consequences of rapid loss of kidney function can be profound and long-lasting, experts say.

About one-third of patients in the study were on higher doses of the cholesterol-cutting drugs, which were defined as rosuvastatin (Crestor), atorvastatin (Lipitor) and simvastatin (Zocor), taken, respectively, at 10, 20 and 40 milligrams or higher.

About one in 500 patients had to be hospitalized within two years of starting low-strength statins. Those in therapy on the higher-strength medication were at a 15 per cent greater relative risk of kidney injury.

The results throw doubt on the common practice of using higher doses of drugs to cut cholesterol levels lower and lower, said lead investigator Colin Dormuth, assistant professor of anesthesiology, pharmacology and therapeutics at the University of British Columbia.

But the key word is "relative" risk, Dormuth said, adding that for patients the absolute risk is small.

"We're talking about a small effect, but it's still important information for prescribers to have when they are making their treatment choices," Dormuth explained.

The higher-dose medications, including Lipitor and Crestor, have become the world's most widely prescribed drugs with some researchers arguing anyone over 50 should be taking them.

For heart and stroke patients with high cholesterol, statins are considered life-saving drugs, and are often prescribed for people with no history of heart disease. But in younger patients, in women and in those without heart disease, the benefits are small, studies have found.

An estimated 30.3 million prescriptions for the drugs were filled in Canada two years ago, according to IMS Brogan, a prescription-drug tracking firm.

In January, Health Canada updated the labelling for statins, warning users they may be at a small increased risk of developing diabetes, particularly in people with pre-existing risk factors such as high blood-sugar levels and obesity. Other unintended effects linked to statins include degenerative muscle disease called myopathy, liver dysfunction and cataracts.

A commentary that appears along with the study suggests that statins have proven value in the general population when it comes to preventing cardiovascular disease, especially with patients who have had heart attacks, but doctors should prescribe weaker cholesterol-lowering drugs whenever possible to minimize kidney damage.

This is the inaugural study published by the Canadian Network for Observational Drug Effect Studies, established in 2011 by Health Canada with a $17.5-million grant over five years and a mandate to evaluate the risks and benefits of drugs on the market in Canada.

Thanks to the initiative, the network obtained data on millions of patients, said Samy Suissa, who heads the network out of the Lady Davis Institute at the Montreal Jewish General Hospital where he is director of clinical epidemiology.

"We're very proud to be a part of this."

Observational studies are limited in scope compared to controlled, randomized trials so there may be other factors to explain the risk of kidney failure, said Suissa.

"However, the method we used is really a state-of-the-art method, which accounts for hundreds of factors in the clinical files of patients that allows, essentially, to eliminate this possibility. We're very confident of the results," he said.

The network has other studies in the pipeline, including one looking at anti-psychotic drugs that may cause diabetes.

Six statin drugs and their generics are currently marketed in Canada: atorvastatin (sold under the brand name Lipitor); lovastatin (Mevacor); rosuvastatin (Crestor); simvastatin (Zocor); pravastatin (Pravachol); and fluvastatin (Lescol).

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